This application seeks three years of funding support for the 23rd-25th Gordon Research Conference (GRC) on Mammary Gland Biology. This long-established conference is one of just a few annual meetings that falls into the must-attend class for mammary biologists and breast cancer researchers. The meeting aims to integrate research into the how the mechanisms underlying normal mammary gland development and environmental exposures contribute to both the risk and prevention of breast cancer as well as assuring competent lactation to meet the nutritional needs of children around the world. This multidisciplinary conference is the key meeting for the dissemination of findings that reveal the aberrant biological features of breast cancer by placing them into the context of normal function. The unique Gordon Conference format, where researchers share three meals per day and mandated social time over a working week, encourages the friendship and trust that very fosters both incisive discussions and the initiation of collaborative ventures. It is also the only meeting in this highly competitive field that maintains the tradition and expectation of revealing unpublished work. It also offers students and postdocs unprecedented access and exposure with a large number of slots reserved for presentations by this group. The international participation offers opportunities for unique perspectives and collaborations. For all of the reasons above, the demand for places at the Mammary Gland Biology GRC is high, as evidenced by the fact that it is one of the most popular conferences run by the GRC. To meet demand the GRC organization places this conference in their largest venues, and unlike most GRCs, the Mammary Gland Biology GRC is run every year, alternating between European and US sites fostering international collaborations. Even by adopting annual conferences, demand for the meeting routinely exceeds the limits placed on the conference by venue seating capacity. Further, the conference routinely receives high praise from its attendees when polled by the GRC organization, emphasizing the high value this conference provides to the attendees. The Mammary Gland Biology GRC has received unbroken NIH support for more than 6 years. This support has underpinned the success of the conference. To assure the continuity of its success, this proposal requests support for the next three conference years.